THE ESAB WELDING AND CUTTING JOURNAL VOL. 64 NO ......ABB Flexarc cell with ESAB welding kit up and...

TRANSPORTATION EXHAUST SYSTEMS • SHOCK ABSORBERS

MOBILE CRANES • TRUCK COMPONENTS • FERRIESTRAMWAY REPAIR • FORKLIFT FRAMES

• MOBILE MACHINERY

THE ESAB WELDING AND CUTTING JOURNAL VOL. 64 NO. 1 2009

Over 100 years of experience in the design and provision of high quality, technicallyadvanced, welding and cutting solutions. Proud recipient of the Frost & Sullivan 2008 Global Welding Consumables Customer Excellence Award.

ESAB – Putting customers first

Awarded for • Responsiveness to customer needs • Providingvalue-addedtechnologyand

services• Implementationofnewtechnologiesto

improve customer service

• Innovativecustomerserviceandcustomercontactstrategies

• Uniquecustomerexperiencemanagement

Working with customers to improve their profitability and their competitive positions.

Frost & Sullivan recognises outstanding industry achievements by presenting Awards to top companies in regional and global markets. Their teams of industry experts recognise the diligence and innovation required to implement a successful business plan and excel in the increasingly competitive global marketplace. These prestigious Awards are recognized worldwide by the media, the investment community, and end-user markets.

Svetsaren

TRANSPORTATION EXHAUST SYSTEMS

TRAMWAY REPAIR

Dear reader,

The transport and vehicle manufacturing sectors are facing challenging times. The effects of the credit crunch are combining with the growing evidence of economic recession and mounting fears over job security. The knockon effect on consumer confidence has been dramatic and rapid, leading to a precipitous decline in new car sales.

Additional pressure comes from increasing environmental awareness. To protect our planet, car manufacturers are reviewing their strategy in terms of alternative energy sources, recycling and reutilisation of waste, hybrid solutions, lithium batteries, fuel cells, ‘green’ tyres, electrical energy management, “stop and start” systems, etc. These technical innovations may also have an impact on new car sales in the near future.

On the other hand, government bodies are supporting investments in local infrastructure, which has a positive effect on the passenger rail transport segment. Passenger traffic has been growing strongly thanks to a variety of factors such as increasing road and air congestion and major improvements in rail services winning people over from air and road. In a number of regions we can still see the huge investments that are ongoing, creating employment and supporting the economic growth of the nation. Rail transport is experiencing a revival.

This issue of Svetsaren features articles and application stories that illustrate the success of our clients, and the indepth involvement of ESAB as a welding and cutting solution provider for both manual and mechanizedrobotic applications in the transport industry.

Good reading,

Christophe GreGoirESAB GloBAl SEGmEnt mAnAGEr trAnSport

TRANSPORTATION

Articles from Svetsaren may be reproduced without permission, providing reference is given to ESAB and Svetsaren as the original source.

PublisherJohan Elvander

EditorBen Altemühl

Editorial committeeTony Anderson, Klaus Blome, Sabine Loeffler, Christophe Gregoir, Joakim Cahlin, Dan Erlandsson, Björn Torstensson, Nils Thalberg, Annika Tedeholm, José Roberto Domingues, Antonio Couto Plais.

AddressSvetsarenESAB AB Central Market CommunicationsBox 8004 S-402 77 GothenburgSweden

Internet addresshttp://www.esab.comE-mail: [email protected]

Printed in The Netherlands by True Colours

Photo courtesy Volvo Construction Equipment AB, Sweden - see page 50.

Christophe Gregoir

Svetsaren no. 1 - 2009 - 3

36 Weldedtransportatsea. ThealuminiumferriestoHokkaidoIncat builds the world’s largest, most fuel-efficient, diesel powered high speed catamaran ferries.

EMCONTECHNOLOGIESBrazilReduced cycle time for welding catalytic converters with ESAB Arcaloy 409Ti metal-cored wire.

07

05 ESABcorporatenewsflash

Contents

4 - Svetsaren no. 1 - 2009

25 Theultimateweldingrobotwithsuperiorweldingtechnology.

12 Rosio™Robotic friction stir welding of complex components.

16 ESABsupportsmobilecrane specialistHIABESAB strategic partner in robotisation project.

21 ABBroboticspartnersteam-upforNefazAndon and ESAB provide complete robotic welding solution for dump truck walls.

ImprovingfatiguelifewithLowTemperatureTransformation(LTT) weldingconsumablesThe technical philosophy behind the LTT-approach.

27

3%moreshockabsorbersforPSAPeugeotCitroënAutomated production benefits from Marathon Pac.

40

Tramtrac™IIRail repair solution for Riga’s tramways.

43 PerfectweldingfortruckaxlehousingsUse of AristoRod 12.50 wire in ArvinMeritor plant results in significant improvements.

46

Volvotakesshort-cuttorobotisedweldingABB Flexarc cell with ESAB welding kit up and running in one weekend.

Mexicanforktruckmakerboosts productivityESAB OK AristoRod drives down cost of frame production.

HowmanymoreBMW’scomeoutofaMarathonPac?Hydro Automotive Norway speeds-up robotic welding of aluminium cross beams.

50

53

56

ProductNews59 OKTubrod14.111.2mmMetal cored wire for high speed thin plate welding applications.

32

several large plasma and oxyfuel cutting machines, ESAB’s new telescopic column and boom SAW stations, rollerbeds, portable welding machines as well as a long term supply agreement for SAW wire and flux.

Meyer Werft orders largest TELEREXTM TXB built to date. Birthdays do not get much better. Just in time for the 70th anniversary of ESAB Cutting Systems, in July 2008, Meyer Werft of Papenburg placed an order for the largest TELEREX TXB gantry cutting machine built to date - with a track width of 33 metres. Extensively automated, the high precision TELEREX TXB handles all cutting and marking functions for the production of large-sized sheets for shipbuilding. The unit for Meyer Werft is equipped with automated plate position recognition for error-free tool positioning, controlled via a camera system. Start-up is planned for September 2009. The contract was signed at the highest level by Meyer Werft owner Bernhard Meyer, ESAB CEO Jon Templeman and Achim Dries, Managing Director of ESAB Cutting Systems GmbH.

ESAB opens new factories in China. On the 19th March 2008, an opening ceremony was held to celebrate the inauguration of ESAB’s third factory in China - ESAB Welding Products (Weihai) Co Ltd. ESAB chose Weihai, located at the tip of Shandong’s North Eastern peninsular, for it’s close proximity to the rapidly expanding shipbuilding industry in Northern China. The plant produces flux-cored wire, speciality coated electrodes and agglomerated submerged arc flux.

Another exciting milestone for ESAB in Asia was reached with the grand opening of ESAB’s first equipment factory in Asia, for the manufacture of step-controlled MIG/MAG power sources and wire feeders. The factory located in Zhangjiagang, Suzhou province, China, was officially opened by Jon Templeman, CEO ESAB Global, on 25 September 2008. Given ESAB’s emphasis on environment, health and safety, the management

and staff have made a conscious effort to ensure compliance with ISO14001 and OHSAS18001 environmental, health and safety standards.

$1.2M order for robot packages from DANA Argentina. In June 2008, DANA, an automotive manufacturer working for the Volkswagen Commercial Vehicles division ordered Aristo Mig™ robot packages for the retrofit of 81 ABB IRB 2400L welding robots for a new VW pick-up truck to be produced in South America, Europe and South Africa. The order was awarded amidst fierce competition from major international welding equipment suppliers. State-of-the-art inverter welding technology was crucial, but also a maintenance contract - an agreement to keep all ESAB equipment running with original spare parts and no dead times.

ABB offers ESAB arc welding packages on IRB robots. ABB has joined forces with ESAB to offer customers a comprehensive robotics, arc-welding solution with power sources, robot-mounted wire feeders, cable package and Marathon Pac bulk drums with robot quality MIG/MAG wire. Central to the package is ESAB’s Aristo robot package which includes the Aristo™ Mig 4000i or 5000i power source - the latest inverter Insulated Gate Bipolar Transistor (IGBT) power source technology – which supports a variety of arc-welding capabilities, including robotic short arc, spray arc, pulsed arc, high speed welding (rapid arc) and the unique SuperPulse™ technology. The robot package can be delivered with separate U8 control unit, or integrated in ABB’s IRC5 robot control unit. The new package is available with ABB’s reliable IRB1600, IRB1600ID (Integrated Dressing) and IRB2400L robots.

Vestas Wind Towers awards major contract to ESAB. In May 2008, Vestas announced the construction of the world’s largest wind tower manufacturing plant in Pueblo, Colorado, USA - a $250M investment. ESAB Welding & Cutting Products was selected to supply equipment for the greenfield production plant for their proven track record, and the ability to design, deliver and service such a large venture. The contract includes

ESAB CEO Jon Templeman at the opening of one of

ESAB’s new factories in China.

ESAB acquires Linkweld. At the end of July 2008, ESAB acquired the former Linkweld MAG wire plant in Terni, Italy - buying all the assets consisting of the 8,000 m2 building and production equipment. The plant was brought back into operation within 2.5 month and acquired ISO 9001 qualification shortly thereafter. The acquisition is another significant step in ESAB’s growth strategy in Europe

AWS Warren F. Savage Awards for ESAB specialists. ESAB employee Dr Leif Karlsson and former employee Dr Enda Keehan recently received ‘The American Welding Society Warren F. Savage Award’. This award recognises the paper they published in the September 2006 issue of the Welding Journal, which best represents innovative research resulting in a better understanding of the metallurgical principles related to welding. Leif and Enda shared the award with co-authors Professor Hans-Olof Andrén from the Chalmers University in Gothenburg, Sweden and Professor Harshad. K. D. H. Bhadeshia from Cambridge University in the UK for their paper ‘New developments with C-Mn-Ni High strength steel weld metals, Part A – Microstructure’.

ESABcorporatenewsflash



The Nordic Council of Ministers has launched a new website that serves as a window to the world for Nordic solutions in renewable energy technology, research and development, as well as political approaches to sustainable energy use. ESAB was invited to participate, and the result can be seen on www.nordicenergysolutions.org

Frost & Sullivan acknowledges ESAB’s excellence in customer service The “2008 Global Welding Consumables Customer Service Excellence Award” has been presented to ESAB.

“ESAB has developed an exceptional product range in response to customer specific needs,” notes Frost & Sullivan Senior Research Analyst Archana Chauhan. “The company has one of the largest welding consumables product ranges; it has consumables for every welding application type, but also to cater to particular industry segments such as shipbuilding, automotives, pipelines, and pipe mills. They are manufactured under a strict ISO 9001 quality assurance programme, in factories that are ISO14001 approved, worldwide.

“A global presence and widely dispersed manufacturing facilities have facilitated an extensive reach and more effective response to customer needs. The ESAB group has 26 manufacturing plants across the globe and sales offices and distributors in almost 80 countries, enabling ESAB to provide a truly global experience to its customers. It tracks its customer delivery performance on a global basis and constantly seeks to improve.

“ESAB invests heavily in R&D to enhance the quality and productivity of its consumables, while reducing their environmental impact and improving the working environment of its customers.

“Through its regionally dispersed Process Development Centres, ESAB is able to provide rapid technical support as well as customer training. Its internationally renowned specialists – wherever located - are united in a single department and globally deployed to improve customers’ welding productivity.

“ESAB publishes an internationally respected customer magazine ‘Svetsaren’ that covers major welding industry related issues,” comments Miss

Chauhan. “The company also deploys user friendly e-marketing and networking strategies. For instance, the ESAB website has all the information necessary to place orders and redress grievances.”

The Frost & Sullivan Global Customer Service Excellence Award is bestowed each year upon the company which has demonstrated global excellence in a given business function such as sales, marketing, customer service, product quality and supply chain management.

About Frost & Sullivan.Frost & Sullivan, the Growth Partnership Company, empower clients to create a growth-focused culture that generates, evaluates and implements effective growth strategies. Frost & Sullivan employs over 45 years of experience in partnering with Global 1000 companies, emerging businesses and the investment community from more than 30 offices on six continents. For more information about Frost & Sullivan’s Growth Partnerships, visit www.frost.com.

• AMERICANWELDINGSOCIETY(AWS)12THAluminum AWS-AA Aluminum Conference (May 5-6, 2009), Toronto, Canada.

tony Anderson: ConfErEnCE ChAirmAn & introduCtory lECturE.

JAy Ginder: friCtion Stir wEldinG of Aluminium - CuttinG mEthodS for Aluminium AlloyS - roBotiC AppliCAtionS.

• AMERICANWELDINGSOCIETY(AWS).Charting the course in welding for US ship-yards – (June 16-17, 2009), Louisiana, USA.

tony Anderson: how to Avoid CrACkinG in ArC wEldEd Aluminum AlloyS uSEd for mArinE AppliCAtionS.

• IIWANNUALASSEMBLY,12-18July,Singapore dr. Leif KArLsson: thE EffECt of purGinG GAS on

308l tiG root-pASS fErritE ContEnt. dr. Leif KArLsson: EffECtS of AlloyinG ConCEptS

on fErritE morpholoGy And touGhnESS of lEAn duplEx StAinlESS StEEl wEld mEtAlS.

LArs-eriK stridh: ESw Strip ClAddinG And hyBridlASEr wEldinG of lonGitudinAl SEAm of ClAddEd pipE.

dr. MiKAeL soron: EvAluAtinG Control SolutionS for roBotiC friCtion Stir wEldinG

• THERMEC,BERLIN,GERMANY,August25-29th. dr. MiKAeL soron: QuAntifyinG thE uSABility of A

roBot SyStEm for friCtion Stir wEldinG.

• 1STINTERNATIONALWORKSHOPonin-situstudies by synchroton and neutron diffraction, 1-2 September 2009, Berlin Germany dr. Leif KArLsson: influEnCE of plAStiC dEfor-mAtion on thE rESiduAl StrESS diStriBution And fAtiGuE BEhAviour of hiGh StrEnGth StEElS wEldS.

• IIWREGIONALCONFERENCEon“Progressive structural materials and their welding and joining technologies”, 14-16 October, High Tatras, Stara Lesna, Slovakia

dr. Leif KArLsson: miCroStruCturE And propErtiES of hiGh StrEnGth StEEl wEld mEtAlS.

ESABinconferenceKeynote speakers are representing ESAB in the following welding conferences in 2009:


Emcon Technologies is a new company resulting from the acquisition of the exhaust systems division of ArvinMeritor in 2007 by OEP - One Equity Partners. Emcon Technologies Brazil has four plants located in: Limeira-São Paulo (the main plant in Brazil), São Bernardo-São Paulo, Camaçarí -Bahia and Gravataí - Rio Grande do Sul. All are involved in the manufacture of exhaust systems and, together, they supply almost all car manufacturers in Brazil, eg, GMC, Ford, VW, PSA, Toyota and Honda.

The use of advanced materials, coinciding with a high level of competitiveness in the automotive industry, has led ESAB to forge partnerships with its clients in this segment, with the objective of providing ideal welding solutions with a competitive edge. This is exemplified by a recent project with EMCON TECHNOLOGIES – a major international fabricator of exhaust systems – which introduced stainless steel cored wires for ferritic stainless steel in their production.

EMCONTECHNOLOGIESBrazilreducescycletimeforweldingcatalyticconverterswithESABArcaloy409Timetal-coredwire.

roberto Luiz de souzA, ESAB BrASil, São pAulo, BrAzil

ConverterFlange

Resonator

IntermediatePipe

Muffler

Tail PipeFlexCoupling

Manifold

hot end cold end

> 900 ˚C 750-900 ˚C 500-700 ˚C 400 ˚C

0 100ºC 200ºC

300ºC

400ºC

500ºC

600ºC

700ºC 800ºC

900ºC

1000ºC

1100ºC

1200ºC

1300ºC

1400ºC

1500ºC

1992 1997 1998 1999 2002

1600ºC

Year


end components. In Europe, austenitic types are common for the complete system, although a trend towards the use of ferritic types is being seen.

ConsumablesConsumables for welding ferritic stainless steel can be either austenitic or ferritic. Austenitic consumables have excellent weldability and give a weld with an austenitic microstructure and good mechanical properties. The addition of nickel, however, makes austenitic consumables more expensive.Ferritic consumables contain 11-18% Cr, depending on classification, and are not alloyed with nickel. They are micro-alloyed with Ti and Nb as stabilisers to prevent sensitisation. They have good weldability and provide welds with excellent corrosion resistance and good mechanical properties – also at high temperatures. This group of consumables is ideal for welding as they do not have Ni and yet maintain the quality desired for the welding of vehicle exhaust systems components.

The test programme carried out by EMCON, in close co-operation with ESAB, investigated the advantages, in terms of weld quality and productivity, of replacing AWS ER308LSi solid wire with ESAB’s Arcaloy 409Ti (AWS A5.9 EC409) ferritic stainless metal-cored wire, in the production of catalytic converters.

Test programmeThe investigation was carried out in three phases, all focussing on a specific area of the consumables’ performance:• weldabilityandproductivity• weldprofile• chemicalcompositionandmicro-structure

All welding was done with a robot cell for the production of catalytic converters – under real production conditions – enabling an exact comparison between the solid and the cored wire (Figure 3).

Weldability and productivityArcaloy 409Ti was used successfully. Both wires were welded in the non-pulsing short arc mode in Ar/2%O2 shielding gas at 220A/18V (ER308LSi) and 240A/20V (Arcaloy 409Ti).

AcknowledgementWe express our appreciation to EMCON TECHNOLOGIES, in particular to Mr. and Mrs. Luiz Henrique Machado, José Eduardo Lepore and Edson Luiz Geniseli for their support and true team spirit during this project.

IntroductionIn the automotive industry, stainless steels are increasingly being used for exhaust systems at the expense of carbon steel. The use of ferritic stainless steel for exhaust systems was first seen in the USA in the mid-70’s and has since gained popularity due to its excellent resistance to corrosion, cyclic oxidation, fatigue, high temperatures and thermo mechanics. They are ideally suitable for environments with abrupt changes of temperature, mechanical wear and exposure to gases and corrosive condense.

Technical evolution and work temperature of catalytic convertersIn Brazil, stainless steel exhaust systems became standard, from 1991, when a government law forced all cars – domestic or imported – to be equipped with catalytic converters. Since then, the maximum operating temperature of converters has increased, due to developments in the ceramic or aluminium-oxide core (honeycomb) and precious metal coatings, resulting in more dependable and efficient converters (Figure 1).

Figure 2 shows the temperature zones in a complete exhaust system, with the traditional division of ‘hot end’ and ‘cold end’. In the USA and Brazil, ferritic steels are predominantly used for the entire exhaust system – AISI type 439 being a popular choice for hot end applications and the lower alloyed AISI type 409 type for cold

Figure 2. Criteria for material selection.

Figure 1. Development in work temperature of catalytic converters.

Melting of ceramic – breakdown of catalytic converter

Zone of overheating – too high temperature for the catalytic process

Transition zone – temperature almost too high

Work zone – catalytic process of cleaning exhaust gases

Temperature too low for catalytic process


The metal-cored wire was impressive, with low level spatter, flat bead profile and uniform and linear welds (Figure 4 and 5). Arc ignition and arc stabilisation were deemed to be excellent - with minimum spatter at starts and stops – greatly improving the final appearance of the catalytic converter.

Economic results were equally convincing, with 45% higher welding speed and a cycle time reduction of 25% (table 1). Obviously, this accounts for an enormous improvement in productivity for a company in the competitive automotive market. The success of Arcaloy 409Ti in the welding of catalytic converters provides a basis for further testing to optimise welding productivity. The next stage of testing will explore the use of pulsed arc welding.

Figure 3. Cell for the robotic welding of catalytic converters.

Table1.Productivitydata.

Parameters Consumable Difference

Datas Solid wire ER308LSi Arcaloy 409Ti Gain

Base metal AISI409 AISI409

Thickness 1.50mm 1.50mm

Wire diameter 1.0mm 1.2mm

Shielding Gas Ar+2%O2 Ar+2%O2

Welding speed (cm/min.) 113 164 +45%

Welding time (s) 48 33 -31%

Cycle time (s) 60 45 -25%

Figure 4. Detail of converter welded with Arcaloy 409Ti.

Figure 5. Converter welded with Arcaloy 409Ti.


Table3.SampleweldedwithER308LSiwire.

Figure 7. Sample analysis plan.

Table2.Sampleweldedwithmetal-coredwireArcaloy409Ti.0

2

4

6

Measured points

Pen

etra

tio

n (

mm

)

0

2

4

6

Measured points

Pen

etra

tio

n (

mm

)

Table4.Weldpenetration-averageofthreetestwelds.

Average of penetration

Samples Difference (%) Wire Arcaloy 409Ti versus solid wire ER 308LSi

D1 C S

1A +56% -7% +7%

1B +65% -14% +23%

1C +109% +55% -11%

D1 C S

1A 0.50 2.54 5.19

1B 0.43 2.09 5.57

1C 0.44 1.96 4.40

D1 C S

1A 0.32 2.74 4.85

1B 0.26 2.49 4.50

1C 0.21 1.26 4.95

Weld profile Macros were taken to verify weld profile and penetration. Figure 7 shows the weld dimensions measured on three individual catalytic converters welded with Arcaloy 409Ti and ER308LSi solid wire, respectively. Figure 6 indicates where the samples were taken.

Tables 2 and 3 show examples of individual values measured on test pieces welded with Arcaloy 409Ti and ER308LSi solid wire and

Table 4 gives the average of three test welds for both wires.

From these results, it can be concluded that Arcaloy 409Ti shows a wider penetration “S” and “D1”. This is because it has a less concentrated electric arc than solid wire. The wider penetration profile is beneficial in the avoidance of lack of fusion defects - particularly important for this industry. On average, the penetration depth “C” was smaller than from the ER308LSi solid wire. This is also beneficial as it involves thin-plate welding with a potential risk of burning-through.

Chemical composition and micro-structureFigures 8 and 9 compare the micro-structure of welds made with both wires, the result being predictable. The weld metal structure is austenitic for the ER308LSi wire and ferritic for the metal-cored wire. The microstructure of the base material and HAZ remain comparable in type and

Figure 6. Cross sections for sampling.

grain size. Tests with oxalic acid did not reveal any sign of sensitisation at the grain boundaries.Also visible is the wider weld bead with less reinforcement produced by Arcaloy 409Ti – in line with the findings of Table 4.

ConclusionESAB’s partnership with EMCON TECHNOLOGIES in a test programme for the replacement of ER308LSi solid wire with Arcaloy 409Ti metal-cored wire in the robotic welding of catalytic converters, resulted in a dramatic reduction in cycle time, as well as a more favourable penetration profile for thin-plate welding. It formed the basis for wide-scale introduction of Arcaloy 409Ti in EMCON production and paved the way for the application of another type of ferritic metal-cored wire, Arcaloy 430LNb.


About the Author:

roberto Luiz de souzA iS wEldinG proCESS tEChnoloGiSt And tEChniCAl ConSultAnt AutomotivE SEGmEnt At ESAB BrASil, São pAulo, BrAzil.A

Figure 9. Joint welded with Arcaloy 430Ti.

Figure 8. Joint welded with solid wire ER 308LSi.


3D welding tests with Rosio™.


Introduction Friction Stir Welding (FSW) has been used for the high quality joining of aluminium since its invention in the early 1990’s. The superior joint quality results from a solid-state procedure, where no filler material or shielding gas is used. The joint is the result of a rotating tool being forced into the material and traversed along the joint line.

The material, suppressed by the tool’s shoulder, becomes plastic and reforms homogenously

leaving a solid bond between the two pieces.The technique was developed at TWI (The Welding Institute) in the early 1990’s, when ESAB joined a group-sponsored project aiming to develop the process. Commercialisation of the process started a few years later with successful installations at Marine Aluminium (Haugesund, Norway), in 1996, and at Boeing (Wichita, Kansas, USA), in 1998. FSW has gained a sound reputation within the welding community as an easy-to-use, defect-free process.

The joining of multidimensional

joints has been a challenge for

friction stir welding (FSW). This is

because machines are

predominantly built to manage

process requirements rather than

enabling motion flexibility. By using

high-payload industrial robots, a

new field of applications for friction

stir welding can be created.

Meeting the requirements of

‘on-road, on-track, in the air

industries’ for high quality and

repeatability, and providing the

flexibility of traditional welding

robotics, robotic friction stir

welding is ready to face the

challenges. This article reviews

ESAB’s research and development

in bringing to the marketplace the

latest member of the ESAB FSW

family: Rosio™ - robotic friction

stir welder.

dr. MiKAeL soron, ESAB AB wEldinG EQuipmEnt, lAxå, SwEdEnKAri eriK LAhti, phd, mSC, mBA, ESAB AB, GothEnBurG, SwEdEn

RoboticfrictionstirweldingofcomplexcomponentsusingRosio™

Figure 1. Welding tests on Rosio™ Friction Stir Welding robot.


However, FSW still faces some challenges. One of these is the limited work envelope of the machines. If the workpiece is not positioned inside the machine’s work envelope, the resulting weld quality is not guaranteed. Additionally, as the forces required to produce the weld are relatively high (ranging from approximately 1kN up to 100kN), the focus in machine design has been on support of high forces while maintaining stability.

As a result, weld joint geometries using stationary machines are, typically, straight or circumferential. This has led to an interest in using industrial robots for friction stir welding for developments outside the ‘comfort envelope’ of traditional planar machines.

ESAB has been developing robotic FSW since 2003 and, after a successful evaluation period, ESAB FSW Rosio™ is now available for various welding applications.

Power game in FSWThe main advantage gained by using an industrial robot for FSW is the 3-dimensional workspace. But along with the axis configuration needed to achieve this workspace, compliant behaviour is unavoidable. As the robot comes into contact with a rigid object, the structure compresses and leaves erroneous encoder readings. As those readings are fed back to the control system to be used in the continuous planning, the applied motion will not correspond to that intended. And, as

the force experienced during FSW may be at the outer limits of the system’s performance, such behaviour will cause instability and most likely cause the operation to fail.

A common solution to such a problem is force control. By disregarding positional readings in the active direction of the tool and, instead, reading the contact force and regulating it according to a desired value, contact stability is ensured. It is obviously a difficult task, requiring not only experience in robot system dynamics, but also the process. It has, none-the-less, been recognised as a suitable solution not only for FSW, but also in many other in-contact operations in which robots are used.

The ESAB robot prototypeESAB has chosen to utilise a standard industrial robot for friction stir welding, whilst acknowledging the known challenges of force capacity, instability, etc. In order to keep the process entry level threshold low, it was decided that a standard, widely available industrial robot is used as building block for Rosio™.

In order to minimise the effects caused by the process, focus areas for development have been in implementation of adaptive control by mechanically reconfiguring the robot so that the maximum downforce of 500kg can be fully utilised.

The actual welding head consists of a tool adapter, a spindle and a motor. It is dimensioned

to apply maximum torque of 40Nm and rotation speed of 3000rpm. This is sufficient for friction stir welding AA6000-series aluminium alloys in thicknesses up to 5mm.

When integrating the welding head with the robot, two main areas need to be considered. Firstly, the operating area of the robot should not be affected by the addition of the friction stir welding head. Secondly, with a constant distance between the FSW tool and the robot’s wrist, stability is increased and the position of tool centre point is better controlled.Minimum mechanical re-configuration of the robot is needed. However, for FSW the 6th axis is more or less redundant, so the space occupied by that axis is used for housing the welding equipment. This increases stability by locating the FSW tool closer to the wrist.

As previously mentioned, there is always a need for an advanced control system when performing FSW with a robot. This is due to the fact that robots are typically not designed for in-contact operations, and very rarely – if ever - for the contact forces experienced during FSW. With elastic deformation always existing in the system under load, process control is very demanding.

In FSW, operations can be divided into both planar and complex welds. Planar weld seams

Figure 3. 3D welding tests with Rosio™.

Figure 2. The world’s first industrial FSW machine; installed at Marine Aluminium in 1996 and, since then, producing panels for marine applications.


About the Author:

dr. MiKAeL soron, iS QuAlifiEd CAlCulAtion EnGinEEr At ESAB AB wEldinG EQuipmEnt, lAxå, SwEdEnKAri eriK LAhti, phd, mSC, mBA, iS dirECtor EnGinEErinG SAlES At ESAB AB, GothEnBurG, SwEdEn

Table1.Rosio™technicaldata.

Force capacity 13 kN

Spindle torque capacity 44 Nm.

Spindle rotational capacity 3000 rpm.

Reach 2.55m from the origin

Control features hybrid force/position control mode

Tool interface Weldon interface with 25mm diameter

Process monitoring Force (x, y, z); Torque (ix,iy,iz); Position (x,y,z); Tool orientation (q1,q2,q3,q4); Spindle rotation (rpm)

Mains 3ph. - 400V, 50Hz

Weight Robot ~ 2500kg, control cabinet ~ 250kg

Connections 2 Ethernet connections (1 service), RS232 terminal

are performed by traditional machines, or any other 2-dimensional welding technique. Complex weld seams are applied on objects having curved surfaces. The major difference between the two, in terms of path planning, is that the motion of a planar weld may be planned according to a pre-defined fixed coordinate system. The system internally calculates how to orientate the tool in

order to apply a tilt angle defined by the user - like a welding parameter - just by being given the positional coordinates from, for example, teach-programming. The robot system also features the ability to apply a proper tilt or travel angle with relative ease. By implementing welding instructions for the robot’s programming language, including the algorithms to apply the tilt angles for a set of common operation, the operator may program the robot as with any standard robot operation.

ApplicationsOne of the early users of robotic FSW is the automotive industry, where relatively soft aluminium alloys - AA5000 and AA6000-series - are used in thicknesses under 3mm (REF. [2-3]). In these applications, forces under 5000N and tool rotating speeds below 3000rpm are typical. Successful butt-

and overlap-joints on AA6063, AA6082 and AA5754 have been per-formed in order to verify the performance of Rosio™ - first in 2D or planar applications and, later, in a real 3D environ-

ment (Figure 3). For the 3D tests, programs were generated automatically from the CAD-drawings for concave-convex-concave objects as off-line programming.

Welding speeds in the tests were approximately 100cm/min for each of the combinations.The location and orientation of the actual workpiece needs to be calibrated for each workstation. This needs only to be done once if the clamping and fixtures are made properly.

SummaryESAB has developed the Rosio™ 3D welding system for Friction Stir Welding. It is suitable for welding soft aluminium alloys in thicknesses up to 5 mm with good repeatability and quality.

Substantial research has been carried out since 2003 in order to be in position to utilise a standard industrial robot for this demanding process. Modifications in mechanics and complex control algorithms have enabled development that makes robotic friction stir welding a viable process for the manufacturing industry.

References[1] Soron M.J., 2007. Robot System for Flexible

3D Friction Stir Welding, Phd Thesis.[2] Lahti K.E., Gregoir C. 2002. Friction Stir

Welding in automotive and road transport. In: Automotive Purchasing News. Pp. 51- 53.

[3] Lahti K.E. 2002. Tailor Welded Blanks (TWB) by Friction Stir Welding (FSW). In. APT Aluminium – Process and product technology. Pp. 1-8.

[4] Lahti K.E. 2004. Wider Extrusions at Lower Cost by Friction Stir Welding. Proceedings of 8th International Aluminium Extrusion Technology Seminar and Exposition, May 18-21, 2004, Orlando. Florida, U.S.A. Pp. 7.

Figure 4. Applications for Rosio™: Tailor-welded blanks, FSW processing, joining of cooling blocks.

The journey has started – join us!

Robotisedweldingwithmetal-coredwiresmakesproductivityleap.


ESABsupportsmobilecranespecialistHIAB

In 2004, HIAB AB in Hudiksvall, Sweden - manufacturer of truck-mounted

loader cranes - embarked on a project to robotise the majority of their welding

operations within a period of three years. ESAB was invited to join-in as

strategic partner.

inGvAr GustAvsson, ESAB AB, SwEdEn.

A remote-controlled crane mounted on a truck to make holes in the roof of a burning building to release hot combustion

gases – the solution to one of the most dangerous tasks facing firemen.


introduced on a smaller scale in conjunction with the laser cutting of components to give the required cut quality and tolerances.

In 2003, HIAB management decided to step-up robotised welding to an unprecedented level for this type of industry, in reaction to a competitive market and an increasing product portfolio requiring flexible and efficient manufacturing. This resulted in the challenging objective to raise the level of robotising or automation from 23% of 65,000 welding hours in 2004 to beyond 70% of 80,000 welding hours, within a period of three years.

ESAB work in PartnershipFrom the start, HIAB wanted ESAB to be involved as a strategic partner and supply welding expertise to the project – the reward would be the associated supply of welding consumables and equipment. To reach HIAB’s objectives, a clear set of responsibilities was defined for ESAB:

• Tointroducenewmethodsandconsumables• Togiverecommendationsforeachapplication• Tooptimiseweldingparameters• Toeducateoperators

The next step was a meeting at HIAB AB between ESAB specialists and HIAB production management to review existing production and decide on a test programme. This resulted in the definition of two sub-projects which, when successful, would provide a sound basis for further robotisation and contribute significantly to HIAB’s objectives.

Test programmeFigure 1 shows the principal components of a truck-mounted loader – the base, loader body, first boom, second boom and extensions.

About HIAB HIAB is part of the Cargotec Corporation - the world’s leading provider of cargo handling solutions for ships, ports, terminals, distribution centres and local transportation links. HIAB specialises in on-road load handling solutions with a complete product offering for loading and delivering goods. It has production plants in 11 countries, sales offices in 34 countries and importers and distributors in 100 countries around the world. HIAB’s world famous brands include HIAB loader cranes, MULTILIFT demountables, MOFFETTandPRINCETONPIGGYBACK®truck-mounted forklifts, ZEPRO, AMA, WALTCO and FOCOLIFT tail lifts, and LOGLIFT and JONSERED forestry and recycling cranes. HIAB AB in Hudiksvall produces truck-mounted cranes with a lifting capacity of up to 28 tons.

Welding optimisation at HIAB ABThis project - to robotise the majority of welding operations within three years, as from 2004, was part of a wider programme of production improvements. Earlier - as part of a major project towards faster, cheaper and higher quality production - robotised welding had been


Gaining a higher welding productivity had been the most important aspect from the onset. HIAB staff and managers were pleased to see that the change from solid wire to OK Tubrod 14.11 ø 1.4mm resulted in a substantial reduction of the cycle time for welding first booms. In a later stage of the project, after implementing the cored wire fully into production, HIAB quantified this improvement to be 20-40%, depending on the component.

The test programme reviewed the manufacturing of the following components:

• Theloaderbody.This involved the production of loader bodies for 10-15 different types of cranes. The objective was to replace manual welding with solid or cored wire by robotised welding with the OK Tubrod 14.11 ø 1.4mm metal-cored wire (SFA/AWS A5.18: E70C-6M H4/EN758: T42 4M M3 H5), advised by ESAB. This is largely concerned with fillet welds - the throat thickness depending on the loader body type. Three loaders where sent to the ESAB Process Centre for testing, to determine parameters for robotic welding with a new ABB robot cell.

• Thefirstboom.This was one of the components already welded by robot, but using solid wire. HIAB was not satisfied with the performance of the solid wire, especially the arc ignition. Frequently the robot would shut off, because of poor arc ignition, and the operator needed to start-up the process again. This problem could not be overcome satisfactorily by precise regulation of the arc characteristics. Also the amount of spatter and the associated cleaning of work pieces were disadvantages. The objective was to increase productivity and, at the same time, to improve

the start/stop behaviour by using a new consumable. Again OK Tubrod 14.11 ø 1.4mm was proposed by ESAB and 3 beams were sent to the ESAB Process Centre for testing.

An additional test involved the manual welding of the most critical weld in the base – an area of high fatigue load – with OK Tubrod 14.11 ø 1.4mm. Weld quality in this safety component is essential and ESAB was able to provide better weld penetration and tie-in, and so improve security.

Green light for cored wireThe tests in the Process Centre - witnessed by HIAB welding staff - gave positive results for all components. Optimal parameters were selected and programs were written for the robotic welding of the individual components. Weld appearance, tie-in and weld penetration fully met HIAB’s quality standards. The start behaviour of OK Tubrod 14.11 was good. The arc establishes faster and with less spatter than experienced in production with solid MAG wire.

Figure 1. Principal components of a truck-mounted crane.

Figure 2. Robotic welding station for welding 2nd booms. Consumable

OK Tubrod 14.11-1.2mm from MarathonPac. Manipulator robot ABB IRB 7600

and welding robot ABB IRB 1400B.


needed to produce the wide product portfolio. Components for a great variety of truck-mounted cranes are recognised by the welding robots through bar codes or optical scanning and welded with the correct program.ESAB’s OK Tubrod 14.11 ø 1.4 metal-cored wire is now universally applied and fed to the robots from Marathon Pac bulk drums. Components with joint types that can only accommodate a limited amount of weld metal are welded with 1.2mm diameter wire.

Everyone of HIAB’s welding staff is pleased with the performance of the cored wire - giving consistent feeding, minimal spatter and, above all, high deposition rate. They report lower cycle times (20-40%), and less post weld work(30-40%).

Unit production savings One component, for example, needed to be produced in a quantity of 8800 pieces per year. In the previous set-up with solid wire, it was not possible to produce these within two-shifts. This meant some 400 extra hours overtime were needed each year, requiring the purchase of an extra robot to solve this bottle-neck.

With OK Tubrod 14.11 ø 1.4mm the cycle time went down from 12 minutes to 8 minutes and it became possible to produce the required quantity

within standard two-shift production and without having to invest in a new robot and without dedicating any floor space.

ImplementationDuring the early stages of the project, ESAB dedicated one of its robotic welding specialists to support HIAB in implementing OK Tubrod 14.11 ø 1.4mm into production and train the operators. The focus of the first visit, in April 2004, was to find optimal parameters for welding loader bodies and program the new ABB IRB 2000 robot. Programs were devised for a variety of loader bodies with fillet weld sizes ranging from a-3 to a-7 at travel speeds of 120 to 42 cm/min - in 92%Ar/8%CO2 shielding gas.

During the second and third visits in May 2005, operators for new robot stations were trained and all robotic cored wire welding was reviewed to see if welding parameters could be further optimised to increase the welding speed. However, most of the parameter settings appeared to be good, needing minimal changes for optimisation.

It’s all robots todayHIAB AB reached its target of robotising 70% of all welding within a period of three years and, with 9 robots in operation today, the level has exceeded 80%.In addition, much attention was given to the organisation of an efficient internal work-flow, to get the most out of the productive robot stations. Systems are in place to provide the flexibility

Figure 3. OK Tubrod 14.11-1.2mm applied for welding loader bodies with limitations to

the amount of weld metal deposited. A mix of small fillet welds and circular welds.

Figure 5. Straight welds or circular welds – OK Tubrod

14.11 is flexible and delivers a good weld appearance.

Figure 4. Manual welding of crucial safety components in the crane base with OK

Tubrod 14.11-1.4mm. These welds need to have a full penetration and a perfect tie-in

to provide high fatigue resistance. This joint is 100% US and X-Ray tested.

About the Author:

inGvAr GustAvsson iS kEy ACCount mAnAGEr At ESAB AB, SwEdEn.

Figure 1. The KAMAZ 6520 dumpster truck. Note the lateral wall with reinforcements for which the robotic welding

stations have been designed.


Andon Automation Andon is an independent robot integrator and strategic partner with ABB for robot based automation. The company has its roots in ABB and, earlier, in the robotics division of ESAB. It develops total robotic solutions - outside ABB’s standard portfolio - for the global market. Since the beginning of 2004, Andon has supplied 130 systems to 105 customers in 19 countries - some 60% being exported outside their Swedish home market. Many were turnkey projects involving planning, design, build/delivery and production start-up.

25,000 dump truck containers a year Contact between Nefaz and Andon was established through EuroTechProm, a Russian confirming house with its head office in Hamburg, following a lead from ABB Germany which recognised the need for a specialised robot integrator and business partner. Nefaz’ objective was as straightforward as challenging: “we want to increase our output to 25,000 dump truck containers a year”. The company is located in Neftekamsk, some 200km from the Kazachstan border, and employs

Russian automotive company

Nefaz, a manufacturer of buses,

tanks for tank trucks and a

supplier to KAMAZ trucks, is

implementing a strategy for the

automation and robotisation of

their, mainly, manually welded

production. As a first step, robot

integrator Andon Automation

provided six gantries, each having

two suspended robots, equipped

with ESAB’s W8 Robot Package –

a welding solution specially

developed for ABB’s IRB 1600,

1600ID and IRB 2400L industrial

welding robots. Andon was

responsible for the full project –

from design through installation to

start-up.

phiLip hoLst, Andon AutomAtion, ÖrEBro SwEdEn And ALex JirofLé, ESAB holdinGS ltd., london, uk.

ABBroboticspartnersteam-upforNefazAndonandESABprovidecompleteroboticwelding solutionfordumptruckwalls.


around 2000 welders in its 11,000 workforce. It drastically needs to step-up production to meet the explosive growth demand of their most important client, truck producer KAMAZ. Nefaz manufactures the walls - two lateral and one rear – and mounts them on three different types of KAMAZ trucks (Figure 1). The reinforcements on the lateral walls are similar to troughs used to reinforce bridges and are fillet welded onto the wall - with the astonishing total weld length being 1709 km per year. Nefaz had in mind the following objectives for this project: •Toensureoutputof25,000containersayear•Tointroduceroboticproductionwelding•Toimproveproductionstandards•Toobtainaconsistentlyhighweldquality•Toreducethenumberofweldersworkingin

harmful conditions

This is a great challenge for a company not familiar with automated and robotic welding and they quickly recognised that the right partners would be crucial to the success of the project.

Six robot stations can do the job Andon did not have to begin from scratch.

Nefaz management and commercial partner, EuroTechProm, provided full information and ideas for production automation - which was particularly helpful in the initial stages of the project. Following various detailed discussions in both Örebro, Sweden, and on site in Neftekamsk, Andon’s wide experience in automation, and capability to think outside the existing production situation, resulted in a solution based on six gantry stations, each equipped with two suspended ABB IRB2400L robots (Figure 2). Each station consists of two tables: one for tacking/welding and one for unloading/loading. When ready, the gantry with the two robots moves to the other table to start tacking and welding the next container wall, while the completed container wall is being unloaded and new components are loaded. The robotic production lay-out is designed for optimal work flow. Components for the lateral and rear walls are lifted by crane to their corresponding locations in the aisle of the hall, while completed walls are unloaded to the perimeter of the fabrication area for transportation. System details Robots are of the 6-axis ABB IRB2400l type; one

of the world’s most popular industrial welding robots. By suspending them in a portal a 7th axis is created. The IRB2400I robot is specifically developed to optimise the efficiency of robotic welding. Its form, arm length and movement pattern are completely dedicated to arc welding with 1.8m reach and 7kg load capacity. It offers increased production rates, reduced lead times and long intervals between maintenance. The robots are equipped with ESAB’s W8 Robot package which is described in detail on page 25 of this issue of Svetsaren. This is an integrated solution for ABB robots. It uses an adapted version of ESAB’s Aristo Mig 5000i power source with the latest IGBT inverter technology (photo page 25). It communicates (CAN bus) with ABB’s IRC5 robot control unit through the W8 interface which is mounted on the back of the power source and is connected to the robot’s cabinet by the W8 connection cable. The system has the advantage of using a minimum amount of cables, which increases operational reliability. All programming is via the IRC5 control unit (Figure 3).

Other components of the W8 Robot package are the AristoTM Robofeed 3004w ELP wire feeder and the Marathon PacTM bulk wire drum. The wire feeder is an encapsulated type with windows for

Figure 2. One side of a gantry welding station during test welding at Andon. The complete station consists of two welding tables with fixtures, one gantry, two suspended

IRB2400L ABB robots equipped with the ESAB W8 Robot package, including two Marathon Pac bulk drums with 250 kg of OK Autrod 12.51 MAG wire.

Figure 4. The SmarTac seam finder corrects for any misallignment

of the workpiece.

Figure 5. AWC; a combined process controller and joint tracking system.

Figure 6. The ABB Torch Service Centre


wire for minimal downtime for wire renewal. The endless Marathon Pac system is an option for zero downtime. For the Nefaz installation, Andon has opted for the 250kg version, placed on platforms on the gantry, see photo page 20. The welding wire is 1.2mm OK Autrod 12.51.

The welding system has a number of advanced accessories; the SmarTac seam finding sensor, the Advanced Weld Controller (AWC) for seam following and a torch service centre.

SmarTac (Figure 4) is a flexible, versatile system that searches for and locates weld positions to adapt the programmed path of the robot to correct for any misalignment of the workpiece. It energises the gas nozzle with an electric charge when in the search mode. When the nozzle and the workpiece make contact, it sends a stop signal to the robot’s control system. After comparing the actual position of the workpiece with the programmed position, the welding program is adapted to the actual position. With SmarTac, quality problems due to misalignment are largely avoided. Since SmarTac is based on electrical contact between nozzle and workpiece, it can only be used for unpainted, conductive materials.

AWC is a combined process controller and “through the arc” joint tracking system integrated in the robot’s controller (Figure 5). It is designed to

track welding joint variations and monitors and controls tracking, weld movement and the welding process. AWC follows weld joints by sampling the welding current and voltage signals synchronised with the robot weave pattern and provides vertical and horizontal correction signals

to the robot controller to ensure a consistent fill of the weld joint. The Torch Service Centre (Figure 6) has three different functions built into one unit: •Thetorchcleanerisanintegratedsystemfor

the mechanical removal of spatter that is fully controlled by the robot control unit to make sure the cleaning won’t start until the torch is

visual inspection of the feeding mechanism. It has the ELP (ESAB Logic Pump) switch that ensures water-cooling is only provided when a water-cooled torch is connected. The Marathon Pac bulk drum provides an uninterrupted supply of 250 or 475kg of welding

Figure 3. All programming, both for the robot and the

welding equipment, is done with the IRC5 control unit.

Figure 7. The six welding stations installed at Nefaz.


securely clamped, and to avoid accidental starts and associated risks for the operator.

•Thewirecutterprovidesconstantwirestick-outfor good arc striking and avoidance of oxide inclusions in weld starts.

•TheBullsEyeisatoolusedfortheautomaticchecking of the Tool Centre Point (TCP). Regular TCP checking is needed because the torch may be out of position due to:

- a robot crash caused by improper programming

- the robot hitting a fixture clamp left in the wrong position

- changes in ambient temperature, eg, morning vs afternoon

- a worn contact tip that causes mis-positioning of the weld

Each time the robot goes to the BullsEye, quality production will continue if the TCP is within the pre-defined tolerances. Otherwise, BullsEye will stop the robot and inform the operator. The stationary gantry, welding tables and fixtures, are all designed by Andon.

Nefaz actively involved This type of project requires intensive co-operation between the robot integrator and the customer to make sure the design is based on the right data and meets the objectives. Nefaz

was involved throughout the project. They provided full data for Andon to create the correct design and calculate the number of stations needed. This was then confirmed by the welding productivity data based on samples of lateral and rear walls sent to Sweden for testing. They calculated if there was enough time – within a welding cycle – to unload the welded truck wall from the table and to load new components plus the quantity of workers needed to do this. Nefaz also calculated the shielding gas consumption and organised the logistics and prepared the electricity supply for the stations. Nefaz production management was present in Sweden during the test welding and supervised the programming of the welding sequence on production samples carried out by an ESAB robotic welding specialist. A very important aspect of the project was the three week “train the trainers” course organised by Andon for station operators, in Sweden. They received basic technical system knowledge and were trained to program the robots – preparing them to be the teachers in the factory.

Installation, start-up and service Installation was carried out in three steps, two gantries at a time, in order to get production started as soon as possible. Technicians from

Andon, with assistance from Nefaz-personnel, installed the systems in an already prepared part of the factory. By the time that the last two were being installed, Nefaz already had production up and running in the first two - a big step towards the production goal of 25,000 containers a year.

The rate at which Nefaz learned to program and use the system is testament to the expertise level of the technicians, as well as the ease of use of the interface in the ABB-control with the power source integrated. Since both ABB and ESAB have service organisations in Russia, Nefaz need have no worries about the availability of spare parts and support of qualified personal, if needed.

Close cooperation between Nefaz and Andon has resulted in a highly productive system, based upon high quality products and support from ESAB and ABB. With the management vision at Nefaz, and the immense potential in the production facilities, all signs indicate that more robots will soon be implemented.

About the Author:

phiLip hoLst iS projECt mAnAGEr At Andon AutomAtion AB, ÖrEBro, SwEdEn.ALex JirofLé iS roBotiC-mEChAniSEd AppliCAtionS Co-ordinAtor At ESAB holdinGS ltd., london, uk.

Aristo TMRoboFeed

Robot controland cable

Powersource

W8

WireMarathonPac TM

Robot

D1

D2

C

A

B

D3


ALex JirofLé, ESAB holdinGS ltd, london, uk.

Figure 1. The ESAB W8 Robot package.

Figure 2. The Aristo™Mig U5000iw.

Combining the best of each partner’s expertise in welding and automation, the new, comprehensive package includes ABB’s versatile, high performance IRB1600, IRB1600ID or IRB2400L robots, ESAB’s Aristo W8 robot package and the client’s preferred choice of torches. The robots are available direct from ABB’s factory in Västerås, Sweden, and are ideal for the welding of carbon steel, stainless steel and aluminium.

The robots feature ESAB’s Aristo W8 robot package - a complete set of welding equipment and consumables, based on ESAB’s latest digital power source technology. The package consists of:• TheAristo™MigU5000iwinverter.• TheAristoW8interfacewhichcommunicates

with ABB’s IRC5 robot control unit.• TheRobofeed3004wELPencapsulatedwire

feeder.• Cablepackages.• TheMarathonPacbulkdrumwithrobotquality

welding wire and separate bobbin holder.

The Aristo™Mig 5000iw inverter.This inverter represents ESAB’s latest generation of digital power sources with up to 500A/39V at 60% duty cycle, designed specifically for robotic MIG/MAG welding in metal fabrication industries. It supports a variety of arc-welding capabilities, including robotic short arc, spray arc, pulsed arc, high speed welding (rapid arc) and the unique SuperPulse™ technology. The power sources are compact and sturdy, based on inverter Insulated Gate Bipolar Transistor (IGBT) technology and an

advanced process regulator. Combined, these offer reliability with outstanding welding characteristics, providing excellent control with a minimum of spatter - even at high welding speeds.It is an easy to use power source with the user-friendly control facilities built-into the ABB’s IRC5 robot control unit, communication with the robot cabinet being through the W8 interface on the back of the power source and the W8 connection cable (CAN Bus/Device Net). It features the full library of ESAB synergic lines for un/low-alloyed steel, stainless steel, aluminium and MAG -brazing and, in addition, the ABB synergic lines developed for thin-plate welding. This is important for both new robots and retrofitting because the same synergic lines can be used.

The Aristo™Mig U5000iw is a multi-process power source which can also be used for manual welding, eg, tack welding, TIG dressing and gauging. A reserve power source, used for

ABB and ESAB, have joined forces

to create the ultimate arc welding

robot - designed for ‘plug and

play’ within half a day.

Theultimateweldingrobotwithsuperiorweldingtechnology

7500

Pin socket Lumber 5-polig Sleev plug Burndy 12-polig12345

Shield+24VOVCan HCan L

FDEKL

RedBlackWhiteLight blue

001 002 003


manual welding, is optional for robot installations.

The Robofeed 3004w ELP encapsulated wire feederThis encapsulated, robot mounted wire feeder is 4-wheel driven. The digitally controlled, twin-motor feed unit provides accurate speed control by using a pulse encoder in the range from 0.8 to 25m/min. It is available with Ø30mm rollers for wires up to Ø1.6mm. It has all important functions for robotic welding such as manual forward and reverse inching, shielding and cleaning gas purge, gas sensor, air test and anti-collision detection, which are accessible through the IRC5 control unit via Can bus communication. ESAB’s TrueArc-VoltageTM system is built-in for continuous measurement of the arc length. Windows in the casing allow visual inspection of the feeding mechanism without having to open the feeder.

The wire feeder is easy to connect/disconnect by using quick connectors for gas, liquid, control signals and welding current, as well as a Euro connector for the welding torch and a quick connector for Marathon Pac.

The Robofeed 3004w ELP features the ELP (ESAB Logic Pump) switch that ensures water-cooling is only provided when a water-cooled torch is connected.

The units are equipped with mounting bolts with rubber absorbers to protect the components from the robot’s high acceleration and retardation forces. Standard and custom mounting plates are available.Robofeed 3004w ELP features:

• Gastest(alsofromrobotandU8)• Reversewire(alsofromrobotandU8).• Inching(alsofromrobotandU8).• Outletsforwatercoolingandaircleaning.• Lampshows42Vpowerison.

Remote Outlet for:• Gastest,reversewire,inchingfromthetorch.• Push-Pull.• Connectionoftheanti-collisionsignal.

Cable packages Cable packages connecting the Aristo Mig 5000iw power source to the Robofeed 3004w ELP wire feeder are available in 7.5m and 10m lengths for the ABB IRB 1600, IRB 1600 ID and IRB 2400L welding robots. Other lengths are available on request.

MarathonPacThe ESAB Marathon Pac family offers a choice of three drum sizes for a variety of wire types - including robotic quality wires such as OK AristoRod, Matt Stainless types and OK Tubrod 14.11 –1.2mm - all of which can be incorporated in the W8 robot package. Marathon Pac minimises downtime for wire renewal. There is, in addition, an endless version which completely eliminates downtime for wire changing. With Endless Marathon Pac, a new drum is connected to the one in use, while the robot continues to weld.

Marathon Pac provides trouble-free, low-force wire feeding, allowing the use of a lightweight wire feeder and reducing wear on both the feeder and the robot.

TheMarathonPacTMfamily–wiregradesandfillingcontent. Standard Jumbo Mini Endless Marathon Pac Marathon Pac Marathon Pac Marathon Pac W x H 513 x 830 mm 595 x 935 mm 513 x 500 mm 2 x standard or jumbo

Non and lowalloyed steel Solid wires 250 kg 475 kg 2 x 250 kg (Ø 0.8 mm: 200 kg) (min Ø 1.0 mm) 2 x 475 kg Cored wires Depending on typeSAW wires Ø 1.6 mm: 475 kg Ø 2.0 mm: 450 kgStainless steelSolid wires 250 kg 475 kg 100 kg 2 x 250 kg (Ø 0.8 mm: 200 kg) (min Ø 1.0 mm) 2 x 475 kg Cored wires Depending on typeAluminium Solid wires 141 kg Copperbased MIG-brazing wires 200 kg

Figure 3. W8 interface on back side of powersource. Figure 4. W8 connection cable to IRC5 robot cabinet.


Fatigue cracks often initiate at welds as a consequence of large residual stresses and changes in geometry acting as stress concentrators. Typically, the weld root (Figure 1) and the weld toe are critical points. A promising concept in improving welded component fatigue life is the use of so called LTT welding consumables. These modify the residual stresses at welds and can even replace the large tensile stresses normally found with compressive stresses. Some aspects of welded component fatigue are discussed in this paper and the concept of LTT-consumables is introduced using results from earlier and ongoing studies.

Why higher strength doesn’t increase fatigue life?Using high strength steels and corresponding high strength welding consumables would seem the obvious and simple answer to demands on decreased energy consumption and increased load-bearing capacity of vehicles. This, unfortunately, is only partly true since strength in itself is only one parameter that needs to be taken

into account in designing fatigue loaded constructions. Most of a welded component’s fatigue life is usually spent in propagating a crack. Since the crack propagation rate is determined by the elastic behaviour of the steel, which is similar for steels of various strength levels, strength will have little effect on fatigue life. As illustrated in Figure 2, fatigue strength of an unwelded component will increase with strength but will remain more or less constant for a welded item.

Figure 2. Effect of tensile strength on unwelded and

welded component life.

Improvement of fatigue lifeApart from obvious factors such as cracks, lack of fusion or other weld imperfections, there are basically two main reasons for the deleterious effect of welds on fatigue properties. Firstly, a weld inevitably introduces a change in geometry and, consequently, a stress concentration, typically at the root or the weld toe. The sharper the transition between the weld and the parent material, the higher the stress concentration will be and thus the greater the effect on fatigue life. The weld profile can be improved by, for example, TIG-dressing or grinding to reduce the stress

As a method of increasing fatigue

life, the use of Low Temperature

Transformation (LTT) welding

consumables has been proven

theoretically and in laboratory

tests. However, the step from

laboratory to real fatigue loaded

construction has still to be taken

to make the LTT-approach

successful. This article discusses

the technical philosophy behind

LTT-consumables.

Leif KArLsson, ESAB AB, GothEnBurG, SwEdEn

ImprovingfatiguelifewithLowTemperatureTransformation(LTT)weldingconsumables

Figure 1. Fatigue crack growing from a weld root.


concentration factor. However, in fillet welds, particularly, it is not possible to completely eliminate the geometrical effect of a weld. An example of a fatigue test specimen showing crack initiation and failure at the fillet weld toe is shown in Figure 3.

Secondly, welds contribute to shortened fatigue life because welding introduces tensile residual stresses. This is a consequence of shrinkage during cool down from the liquid state to room temperature. These stresses are significant and often of the order of the yield strength. The conventional way of coping with high weld residual stresses is to reduce design stresses, or to conduct a post-weld heat treatment to relieve the residual stresses. Another approach is to introduce surface compressive stresses by locally deforming the surface by, for example, shot- or hammer-peening. Stresses can also be redistributed by plastic deformation, ie, overloading a construction. All these techniques are efficient in increasing fatigue life but require additional work after welding.

Effect of stress distributionRedistribution of stresses by plastic deformation

has its limitation in practice, as many constructions are not easily deformed in a well-controlled manner. However, the technique is well-suited for studies of the influence of stress distribution at welds, since the welding procedure

and, thereby, weld metal composition, structure and properties, can be kept constant.

The example below, from an ongoing ESAB-study, illustrates that there is ample scope for improvement of fatigue life of welds by reduction of residual stresses. An 800 MPa yield strength parent material was welded with slightly undermatching consumables to produce fatigue test specimens (Figure 3). One set of specimens was fatigue-tested in the as-welded condition and one set after straining. Plastic deformation was controlled to about 0.2% at the weld toe to avoid significantly affecting mechanical properties.

Residual stresses of as-welded and pre-stressed specimens were measured 2.5 mm below the plate surface along the specimen centre-line using neutron diffraction (1). As seen in Figure 4, longitudinal stresses changed significantly and decreased with up to 600 MPa in the region around the weld toe. The same trend was found for the other stress components although not quite to the same extent.

The effect on fatigue properties of modifying the stress distribution was striking. As seen in Figure 5, fatigue strength increased significantly and the effect was larger for lower loads. For example, at

Figure 3. Example of fatigue test specimen with fillet welds. When fatigue load is applied in the longitudinal direction (arrows)

fracture is commonly found to initiate at the fillet weld toe The enlargement shows one half of the separated test specimen.

Figure 4. Comparison of residual longitudinal stresses at fillet weld in as-welded condition and after pre-stressing caus-

ing a local plastic deformation of approximately 0.2% near the weld toe.


1) Since the thermal expansion coefficient of austenite is greater than that of ferrite, the volume expansion due to transformation is larger at lower temperatures, allowing a greater compensation of

the accumulated thermal contraction strain.2) If transformation is completed much before ambient temperature is reached, then it is the ferrite that contracts on cooling. Ferrite has higher yield strength than austenite (at low temperature) and hence there is a lesser compensation of contraction strain by plastic relaxation. 3) When transformation occurs at low temperatures there is a greater accumulation of stress before the low transformation temperature is reached. This leads to a greater bias in the microstructure in constrained specimens, making the shear strain more effective in counteracting thermal contraction.

Several alloying concepts using various combinations of, mainly, Ni, Cr and Mn, producing a low Ms temperature have been suggested and tried in the last decade (3-10). Fatigue testing has shown very promising results with increase in fatigue life, often of 25 times or more, and increased fatigue strengths of 50% or more.

An example is presented in Figure 6 giving some results from reference 5. In this study, specimens for fatigue testing were out-of-plane gusset fillet welded joints in 7 mm thick 700 MPa yield

2,000,000 cycles fatigue strength was approximately doubled.

Low Temperature Transformation (LTT) consumablesWelding introduces tensile residual stresses as a consequence of shrinkage during cool down from the liquid state to room temperature. These stresses are significant and often of the order of the yield strength. The shrinkage is to some extent compensated by a volume expansion as austenite transforms into ferrite, bainite or martensite. However, typical steel welding consumable compositions have transformation temperatures around 400-600ºC. As a consequence of further shrinkage on cooling to room temperature the net effect is a contraction resulting in significant tensile stresses.

LTT welding consumables are formulated to have a composition giving a much lower transformation temperature. Typically the aim is to produce mainly martensite with a Ms temperature in the range of about 150-250ºC. The lower transformation temperature combines three effects to be beneficial in reducing the final residual stress level (2).

Figure 5. Effect on fatigue life of modification of residual stresses by pre-stressing. Specimens were loaded axially in pulsating tension with stress ratio R=0.1.

Figure 6. Fatigue life of a 700 MPa yield strength steel welded with undermatching and matching strength

consumables and matching strength LTT consumables (see reference 5 for details).


strength plate material (see Figure 3 for geometry). Specimens were welded with conventional matching and undermatching strength consumables and with matching strength LTT-consumables with a composition of 12.5Cr 6.5Ni 2.5Mo. Testing was done with axial loading in pulsating tension with stress ratio R=0. Waveform was sinusoidal and the frequency varied between 5 and 10 Hz depending on load level. About 10 specimens were tested for each type of welding consumable.

The results confirm both that consumable strength in itself has no effect on fatigue properties and that the LTT-effect can be significant.

DeformationAnother practical aspect, rarely discussed in connection with LTT consumables, is welding induced deformation. Deformation can be a major concern causing problems with fit-up and requiring additional work to straighten components. As shrinkage is the reason for deformation, LTT consumables can be used to counteract this. Figure 7 gives a simple example for two unrestrained mild steel plates (200x50x6 mm) joined with a single pass weld in a square

butt joint. Even though a stainless 308 type consumable would not normally be used for welding mild steel, it serves the purpose of illustrating how the choice of consumable can have a large effect on welding induced deformation.

Concluding remarksSome questions still remain before it can be concluded whether the use of LTT-consumables is a practical method of increasing fatigue strength and minimising welding induced deformation. Effects of multi-pass welding, dilution with parent material and spectrum loads on resulting fatigue properties, needs to be studied further. It also remains to define suitable LTT-alloys that, not only modify the stress distribution, but also provide required static strength and useful impact toughness. Hot cracking could potentially be an issue when using primarily Ni as an alloying element to suppress Ms as this will shift the weld metal into austenitic solidification. Other alloying concepts might, therefore, be safer from the practical point of view.

Nevertheless, LTT-consumables show promise as an important method for reducing the risk of

welded component fatigue failure. Compared to most other techniques, it has the advantages of being a “one-shot” method, ie, no further treatment is required after welding. As a bonus, it reduces deformation and decreases the risk of cold cracking (11). This, therefore, is not only a time and cost saving approach, it is also particularly attractive when other techniques such as PWHT or shot peening are not feasible, as is often the case in field repair welding.

A valid objection against LTT consumables is that the effect will decrease or disappear if the construction is subjected to an overload causing plastic deformation and redistribution of stresses. However, this holds equally well for other techniques used to introduce compressive surface stresses and is a common problem, rather than specific to the LTT-concept.

In conclusion, the potential of the LTT-approach as a method of increasing fatigue life has been proven theoretically and in laboratory tests. However, to make it a success story, it still remains to take the step from laboratory tests to real life applications in fatigue loaded constructions.

Figure 7. Deformation of unrestrained mild steel plates (200x50x6 mm) joined with a single pass weld in a square butt joint using two types of consumables.


About the Author:

Leif KArLsson iS SEnior ExpErt & mAnAGEr rESEArCh projECtS At ESAB, GothEnBurG, SwEdEn.

AcknowledgementThe author wishes to thank Dr L. Mraz (VUZ Welding Research Institute – Industrial Institute of Slovak Republic), Professor H. K.D.H. Bhadeshia (Cambridge University, England), J. Eckerlid and T. Nilsson (SSAB Tunnplåt AB, Sweden) and Eva-Lena Bergquist (ESAB AB, Sweden) for comments, stimulating co-operation and providing some of the figures.

References1. Pavol Mikula, Miroslav Vrána, Lubos Mráz, Leif

Karlsson, High-resolution neutron diffraction employing Bragg diffraction optics – a tool for advanced nondestructive testing of materials. Proceedings of the 9th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA08, July 7-9, 2008, Haifa, Israel

2. H. K. D. H. Bhadeshia, J. A. Francis, H. J. Stone, S. Kundu, R. B. Rogge, P. J. Withers and L. Karlsson ”Transformation Plasticity in Steel Weld Metals”, Proc. 10th Int. Aachen Welding Conference, 22-25 October, 2007, Aachen, Germany.

3. A. Ohta, O. Watanabe, K. Matsuoka, C. Shiga, S.Nishijima,Y.Maeda,N.Suzuki,andT.Kubo. ”Fatigue strength improvement by using newly developed low transformation temperature welding material.” Welding in the World, 1999, Vol. 43, pp. 38-42,.

4. A.Ohta,N.Suzuki,Y.Maeda,K.Hiraoka,andT. Nakamura. Superior fatigue crack growth properties in newly developed weld metal. International Journal of Fatigue, 1999, Vol. 21, pp. S113-S118.

5. J. Eckerlid, T. Nilsson and L. Karlsson, ”Fatigue properties of longitudinal attachments welded using low transformation temperature filler”, Science and Technology of Welding and Joining, 2003 Vol. 8, No. 5, pp. 353-359.

6. A.Ohta,K.Matsuoka,N.T.Nguyen,Y.Maeda, and N. Suzuki. Fatigue strength improvement of lap welded joints of thin steel plate using low transformation temperature welding wire. Welding Journal, Research Supplement, 2003, Vol. 82, pp. 78s-83s.

7.H.Lixing,W.Dongpo,W.Wenxian,andY.Tainjin. Ultrasonic peening and low transforma-tion temperature electrodes used for improving the fatigue strength of welded joints. Welding in the World, 2004, Vol.48, No. 3-4, pp. 34-39.

8. J. A. Francis, S. Kundu, H. K. D. H. Bhadeshia, H. J. Stone, R. B. Rogge, P. J. Withers and L. Karlsson, ” Transformation Temperatures and Welding Residual Stresses in Ferritic Steels”, Proceedings of PVP2007 2007 ASME Pressure Vessels and Piping Division Conference, July 22-26, 2007, San Antonio, Texas, PVP2007-26544, pp. 1-8.

9. Ph. P. Darcis, H. Katsumoto, M. C. Payares-Asprino, S. Liu, and T. A. Siewert. “Cruciform fillet welded joint fatigue strength improve-ments by weld metal phase transformations”, Fatigue & Fracture of Engineering Materials & Structures, 2007, Vol. 31, pp. 125-136.

10. F. M. Diez. The development of a compres-sive residual stress field around a weld toe by means of phase transformations. Welding in the World, 2008, Vol.52, No. 7-8, pp. 63-78.

11. SZenitani,N.Hayakawa,J.Yamamoto,K.Hiraoko,YMorikage,T.Kubo,KYasudaandK Amano, “Development of a new low trans-formation temperature consumables to pre-vent cold cracking in high strength steels”, Science and Technology of Welding and Joining, 2007, Vol. 12, No. 6, pp. 516-522.


frAnK tessin, ESAB GmBh, SolinGEn, GErmAny.

OK Tubrod 14.11 ø1.2mm is a new metal-cored wire for non- and low-alloyed steel which has been specially developed for the high speed welding of thin plates (1-4 mm). Treated with ESAB’s revolutionary cored wire surface technology, it sets new standards in the reduction of welding costs, especially in mechanised and robotic stations.

Metal-cored wires have been available for more than twenty years, but their use in industrial applications has, so far, remained limited - the main reason being the relatively high consumables price compared with G3Si1/ER70S-6 solid wire. Metal-cored wires will only be applied in situations where their higher weld quality and welding speed can be seen to be of benefit and can be calculated to be economical. This is the case for OK Tubrod 14.11 in many applications.

The difference in welding performance in the thin-plate area, compared to solid wire, is striking. Many applications can be welded with travel speeds above 150 cm/min, regardless of whether it is thin fillet welds (a=2-2.5 mm) or overlap joints. Here, OK Tubrod 14.11 tends to produce welds without undercut and with nice wash to the plate edges.

Low spatterOK Tubrod 14.11 Ø1.2mm operates in the spray arc mode at a current level as low as 160A providing the widest possible envelope for low-spatter welding with a fine droplet transfer. This is a major advantage compared to Ø 1.0 and 1.2mm solid wires, which can only be used in the short arc or globular arc mode when welding thin plate.

Faster weldingReduction of welding time is key to lower welding costs in mechanised applications. This can be realised through higher welding speed. With common solid wires, however, options are limited in thin-plate welding. High welding speeds are mostly achieved at the expense of weld quality and mechanical properties, which is the reason why the majority of applications are welded in the short arc or globular arc mode, at travel speeds typically below 100 cm/min.With OK Tubrod 14.11 Ø1.2mm, however, travel speeds of 150-250 cm/min are feasible – not only for straight joints, but also for small radius circular welds.

Low-heat input welding – welding of zinc coated plateBecause of high welding speed and an extraordinarily low arc voltage, heat input into the welded part is very low. Fillet welds in 1.5mm thick plates can be welded at travel speeds of 200cm/min. or more, in PB position - at a heat input below 2 kJ/cm!

In Svetsaren 1/2008, page 70, we

introduced OK Tubrod 14.11

diameter 1.2mm – a new

metal-cored wire for high speed

thin plate welding applications,

which provides full information on

product data and welding

performance. The present article

discusses the welding performance

and economic benefits of OK

Tubrod 14.11 1.2mm for robotic

welding.

OKTubrod14.111.2mm

Figure 1. Circular fillet weld. t=2mm, 280A, 22V,

150cm/min.

Metalcoredwireforhighspeedthinplateweldingapplications


This makes OK Tubrod 14.11 Ø1.2mm an alterna-tive to modern, so called ‚“cold arc” welding proc-esses in processing non- and low-alloyed steel.

These advantages also provide benefits in welding zinc-coated plate, where OK Tubrod 14.11 Ø1.2mm stands comparison with very low porosity and spatter.

Secure arc ignitionShort welds with many starts and stops can also be welded at a low spatter level with OK Tubrod 14.11 Ø1.2mm. A stable arc is established a split second after ignition.

Gap bridgingVery often, the limited gap-bridging capabilities of wire electrodes present a problem in spray arc welding at high travel speeds. OK Tubrod 14.11

Ø1.2mm, however, is very forgiving with respect to poor fit-up, bridging gaps even at very high travel speeds - resulting in less post weld repair work and less rejects in serial fabrication.

Easy parameter settingParameter setting with OK Tubrod 14.11 Ø1.2mm is uncomplicated. In the thin-plate area, the arc voltage is between 22 and 24 V – whether one welds at the lowest wire feed speed of 7m/min or the highest of 14 m/min. Parameter setting is further reduced by pre-programmed synergic lines in ESAB Aristo power sources.

Secure penetration in shielding gas mixturesOK Tubrod 14.11 Ø1.2mm can be welded with various mixed shielding gas compositions. The best bead appearance and spatter level are obtained in EN ISO 14175: M20 with 92% Ar and 8% CO2, but also the standard 82%Ar/18% CO2 (EN ISO 14175: M21) mixed gas gives good results. Weld penetration is not noticably influenced by the amount of CO2 in the shielding gas, see Figures 4 and 5. However, the higher amount of silica islands with a higher amount of CO2 is to be taken into account.

Numerous applicationsThe application of OK Tubrod 14.11 Ø1.2mm can potentially bring cost savings in any application involving mechanised or robotic welding of sheet metal up to 4 mm thickness where the welding station forms a bottleneck in production. The cycle time for a station can be substantially reduced, due to the significantly higher welding speed. This enables a productivity increase of 20-40% and a corresponding decrease in welding cost. Applications are found in the fabrication of thin-walled components for the automotive and transport industries in general, but also in, for instance, the furniture industry.

Cost calculationAs indicated earlier, the use of metal-cored wires needs to be proven to be economic in practical situations in terms of cost. The basis for this calculation is the status existing welding station data when using solid wire:

• thearctimeinsecondsorminutes• theweldingspeed• weldmetalweightpercomponent• hourlyrateofwelding,includingoperator

The higher price of the metal-cored wire in Euro/kg – resulting in higher consumables costs per component – must, at least, be compensated by lower fabrication costs resulting from the reduced cycle time.

Figure 2. Weld penetration of an overlap joint in a cross

support beam. t=2mm. 225A/130cm/min.min. Figure 4. Weld penetration profile fillet weld. a=2 mm;

t=2 mm; Vs=150cm/min. Shielding gas: 92% Ar/8%

CO2.

Figure 5. Weld penetration profile fillet weld. a=2mm;

t=2mm; Vs=150cm/min. Shielding gas: 82% Ar/18%

CO2. Figure 3. Overlap joint in 1.2mm zinc coated plate

(layer thickness < 10µm). Shielding gas: M20 (92%Ar /

8% CO2); 240A, 21V; Vs=170cm/min.

Table1.Typicalweldingparametersforoverlapandfilletweldsinthinplate.Shieldinggas:M20(92%Ar/8%CO2)

Jointtype Plate Wfs I U Vs

thicknessmm m/min A V cm/min

Overlap weld 1.5 7.0-8.5 225-250 22.5-24 130-180

Fillet weld; a=2mm 2-3 13-14 310-340 22.5 220

Fillet weld; a=4mm > 8 13-14 310-340 26.5 70


Calculation of production savings:

PCS =Weldingstationcosts,includinglabourcost[Euro/h]XCycletimereduction[s]/3600

Calculation of consumables cost increase per component

The consumable cost increase, when using cored wire instead of solid wire, is around 0.002 Euro/g. Per component this amounts to:

CCI (1) =0.002Euro/gXGWM Alternatively, the consumables cost increase per component can be calculated through the wire feed, which can be retrieved from the wire feed unit or from the welding parameter log of the power source. The effective consumable usage per component is obtained by multiplying the length of wire used per component by the specific weight of the wire (7.8 g/m for OK Tubrod 14.11). This method has the advantage that burn-off and spatter loss is also taken into account.

CCI (2) =0.002Euro/gXWFcXSWW

Calculation of welding cost savings per component.

C = PCS-CCI(1/2)

Fabrication of axle componentsThe following example is based on data obtained from an automotive indudtry application. .

A robot station with a cost of 60 Euro/h, operator included, is used to weld overlap joints in 2mm plate at a travel speed of 12mm/s (72cm/min), using G3S

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